Lead-coating process



PATENT osmcs.

UNITED STATES-.2

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To all whom it may concern Be it known that I, ROBERT J. SHOEMAKER, acitizen of the United States, residing at Chicago, in the county of Cookand State of Illinois, have invented certain new and useful Improvementsin Lead-Coating Processes, of which the following is a specification.

y iron or steel articles, and its object is to provide a method b whichthis operation scribed, may, however,

ing the billets output with a "quired or ma be accomplishe moreconveniently, expe itiousl and economically than with methods eretoforeused. A more specific object of the invention is to improve upon theprocess of manufacturing cold drawn steel tubes by coating the billetsfrom which the tubes are drawn with lead in the novel manner, to behereinafter described, for

the urpose, in the first place, of lubricatin the illets for the drawinoperation an in the second place, giving t e finished tubes a highlypolished rustproof surface. By utilizing the coatin' process in thisconnection the necessit or lubricating or dopefore drawin 'ls obviated(where the billets are not su 'ected to a large number of passes atleast the peroentage of breakers is greatly decreased; the number ofasses to obtain a given reduction of the billet may be diminished; thedanger of scratching the tubes is minimized; wear and tear on the diesand mandrels lessened, thereby increasing the life of thes parts; andthe possible speed of the billets through the draw bench is considerably1ncreased; al-l of which results in increased 'ven equipment and in a.

"van time and ecrease in the manufacturmgLcost of the tubes. In additionthe surfaces of the tubes are made highly polished and rustproof.

- The coating method, to be hereinafter debe used inoth'er connections,for example, coating blanks or bodies to be employed in stamping orations or, in fact, the method may be uti ized in the manufacture ofany iron or steel articles where the coating of the articles with athin, even dense covering of lead is redesirable. With thisunderstanding, the improved method will, be described as .utilizedfortreatment of billets for cold drawin steel tubes, and is as follows:

The hillets are first cleaned in the usual Specification of LettersPatent.

invention relates to the lead coating of way by means of a suitableacid, it being of partlcular importance to remove all traces of grease.They are then immersed in a concentrated water solution of lead acetateand acetic acid. The solution should contain at least thirty-five percent, by weight, of lead acetate, although to get the best results'thelead acetate content should be from forty to fifty per cent. The aceticacid should not be less than five per cent. A somewhat larger quantitymay be used. The solution 18 heated, otherwise the action will beextremely slow. Preferably it is maintained at a temperature from 160 to180 Fahrenheit, which is sufficient to disassociate the ace- 'tatewithout producing excessive volatilization of the acetic acid. If thebillets be allowed to remain for approximately fifteen minutes 1n thesolution at this temperature they will be covered with an extremely thinbut smooth and very dense coating of lead which adheres to the steelwith great tenac-f ltg. Apparently the chemical action is one 0substitution, the lead acetate disassociating and the lead beingdeposited on the bil let and iron from the billet combining with theradical (OJ-1,0,) to form iron acetate. In time this iron acetate willdecompose into 1I'0I1 hydrate and acetic acid andthe iron hydratesettling to,the bottom of the tank,

may be drawn ofi at suitable intervals. The solution will becomeimpoverished during the process and may be built u acetic aci iron andhas a cleansin effect 0 th billets. g up n e .After-the process has beencarried on for a time,:the solution will necessarily contain a eertamamount of iron acetate and while this does not interfere with thecontemlated chemical action the adherence of this iron acetate to thebillets will result in the formation of rust on the plated surface,

through oxidation, so thatit is desirable that the billets, when takenfrom the solution, be washed to remove the iron acetate, or otherwisetreated to prevent the rusting from; 1 5

taking place. Ordinarily it will be sufli- 0161;: to wash the billets tordughly in clean wa r.

The billets thus treated may be drawn m the usual manner through diesand over Patented Mar. 15, 1921. Application filed December 11', mo.8erial1io.429,889.

by adding mandrels. The lead coating makes it unnecessa to cover thebillets with any of the usua lubricants or dope elther before the passor. between lpasses unless the billet 1s given, a consider-a le numberof passes, say .fouro'r more. The usual annealin and pickling betweenpasses is consequent y obviated.

Commercial operation of the process has shown that the billets whentreated as above described may be drawn with less breakage than whendope according to methods heretofore used. 'I have found that the numberof breakers is ordinarily reduced from the usual ten per cent. to aboutthree per cent. In some operations it is ssible to accomplish thedesired reduction y a fewer number of passes than heretofore. The speedof the billets through the draw bench may be increased, thereby makingpossible an enlarged production with a given e uipment and in a giventime. Fewer o the tubes are scratched. Year and tear on the mandrels anddies is diminished, increasing the life of these parts several fold. Thebillets are more conveniently handled than those coveredwith the greasydope ordinarily used. Finally, the finished tubes are given, within andwithout, highly polished surfaces which will not rust. If the tubes areannealed it will be found that they can be flanged, flattened orsimilarly manipulated just as well as the seamless tubes made by the oldprocesses.

This application is a continuation in part of my co-pending applicationSerial No. 374,089, filed April 15, 1920, for lead coating process.

I claim:

1. Method of lead coating an iron or steel article which consists inbringing the same into contact with asolution of lead acetate I tatetherefrom.

3. Method of lead coating iron or steel articles which consists inimmersing the same in a solution of lead acetate of sufficientconcentration to cover the surfaces thereof with a dense, thin, smooth,permanently adherent film of lead which is substantially non-oxidizablewhen exposed to the atmosphere.

4. Method of lead coating iron or steel articles which consists inlmmersing the same in a solution containin not less than thirty-five percent. by weig t of lead acetate.

5. Method' f lead coating iron or steel articles which consists inimmersing the same in a solution containin not less than thirty-five percent, by Weig t, of lead acctate and thereafter washing the articles toremove traces of iron acetate.

6. Method of lead coating iron or steel articles which consists inimmersing the same in a water solution containin approximately forty tofifty per cent, y weight, of lead acetate, and five per cent. or more ofacetic acid maintained at a temperature of between 160 and 180Fahrenheit.

ROBERT JAY SHOEMAKER.

thin, smooth, per-'

